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1982年10月,美国在亚拉巴马州Brookwood煤矿的竖井掘进中,以月(31天) 进尺1622.5英尺的成绩创造了竖井掘进世界新记录。竖井直径23英尺,井深2000英尺,是
In October 1982, the United States made a new record in the world of shaft boring with a logging of 1622.5 feet a month (31 days) in shaft excavation at the Brookwood mine in Alabama. The shaft is 23 feet in diameter and 2000 feet deep and is